The invention discloses a sewage treatment device, which is formed by combining the following seven parallel and communicated tank units: an adjustment tank, a No.1 biochemical tank, a No.2 biochemical tank, a No.3 biochemical tank, a No.4 biochemical tank, a return tank and a discharge tank. Microbes, wood biological carriers and aeration pipes with aeration micropores on the surface and with certain distance from the tank bottom are placed into the seven tank units respectively; the wood biological carriers are matched with directional aeration flow fields to form accumulations of different areas in the tank so that simulated natural environment areas in which the same natural microbes can coexist are formed in the tanks, namely an anaerobic area, an anoxic area and an aerobic area. Therefore, organic substances in the sewage are quickly decomposed; the residual organic sludge phenomenon is thoroughly eliminated; full fermentation, decomposition and digestion for the organic substances are effectively performed; and the whole treatment device does not produce bad smell, does not grow flies, purifies the sewage to form odorless and tasteless purified water, and thoroughly achieves the effect of protecting the ecological environment. The device has the advantages of scientific design and reasonable structure, and is suitable for popularization.